Three-phase rectifier multiple switch open-circuit fault diagnosis method based on voltage deviation

Abstract

The application discloses a kind of three-phase rectifier multiple switch tube open-circuit fault diagnosis methods based on voltage deviation, belong to power electronic converter fault diagnosis technical field.Method includes: obtaining relevant signal for diagnosis;According to three-phase voltage, three-phase current, three-phase inductance value, three-phase equivalent resistance value and switching period, the actual value of three-phase line voltage is calculated;According to DC voltage and the duty cycle of switch tube on three-phase bridge arm, the expected value of three-phase line voltage is calculated;Difference is obtained between the expected value and actual value of three-phase line voltage;The deviation value of three-phase line voltage is compared with first preset threshold and second preset threshold, to determine the polarity of the deviation value of three-phase line voltage;Wherein, first preset threshold is less than second preset threshold;The polarity of the deviation value of three-phase line voltage is combined with voltage phase, to determine fault switch tube.The application can quickly diagnose for various situations of multiple switch tube fault, including single switch fault, two switch tubes in succession fault, two switch tubes simultaneous fault.

Description

Technical Field

[0001] This invention belongs to the field of power electronic converter fault diagnosis technology, and more specifically, relates to a method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation. Background Technology

[0002] Three-phase two-level voltage source rectifiers (VSRs) are widely used in motor drives, power quality control, and other fields due to their outstanding advantages: low harmonic content in grid-side current, unity factor, and bidirectional energy transmission. The safe and stable operation of the rectifier is crucial for these applications. A three-phase two-level VSR typically contains six switching transistors, with two transistors per phase arm. The transistor connected to the positive DC terminal is usually called the upper arm switch, and the transistor connected to the negative DC terminal is called the lower arm switch. These switching transistors are key components in power conversion, requiring high-frequency switching on and off. Studies show that switching transistors are among the most prone to failure in power converter systems. An open-circuit fault in a rectifier switching transistor will cause AC current distortion and DC voltage fluctuations. Prolonged operation with this fault will increase the switching stress on other normal switching transistors, leading to secondary faults and ultimately equipment shutdown. Therefore, quickly and accurately locating the open-circuit faulty switching transistor is of great significance for ensuring the safe operation of the rectifier.

[0003] In existing research on open-circuit faults in rectifier switches, most diagnostic techniques are limited to diagnosing single open-circuit faults, with few methods applicable to both single and two open-circuit faults. Currently, among diagnostic methods for multiple open-circuit faults, hardware-based methods offer faster diagnostic speeds but require additional sensors, increasing cost and system complexity. Software-based methods, on the other hand, require tens of milliseconds to diagnose multiple switch faults. If diagnostic speed could be improved without adding extra hardware, and if various scenarios involving multiple open-circuit faults—including single-switch faults, sequential faults of two switches, and simultaneous faults of two switches—could be diagnosed quickly, significantly improving the reliability of rectifier operation. Summary of the Invention

[0004] In response to the shortcomings and improvement needs of existing technologies, this invention provides a method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation. The purpose is to solve the technical problem that existing diagnostic methods for open-circuit faults of multiple switching transistors cannot simultaneously achieve low cost, low complexity, and high efficiency.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation, comprising the following steps:

[0006] Obtain the three-phase voltage, three-phase current, DC voltage, duty cycle of the switching transistors on the three-phase bridge arm, voltage phase calculated by the phase-locked loop, three-phase inductance value, three-phase equivalent resistance value, and switching cycle of the rectifier;

[0007] Based on the three-phase voltage, three-phase current, three-phase inductance, three-phase equivalent resistance, and switching cycle, the actual value of the three-phase line voltage is calculated according to Kirchhoff's voltage law; the expected value of the three-phase line voltage is calculated based on the DC voltage and the average duty cycle of the switching transistors on the three-phase bridge arm; the deviation value of the three-phase line voltage is obtained by subtracting the expected value from the actual value.

[0008] The deviation values ​​of the three-phase line voltages are compared with a first preset threshold and a second preset threshold to determine the polarity of the deviation values ​​of the three-phase line voltages; wherein the first preset threshold is less than the second preset threshold.

[0009] By combining the polarity and phase of the deviation values ​​of the three-phase line voltages, the fault switch transistor can be determined.

[0010] Furthermore, the actual value of the three-phase line voltage is calculated as follows:

[0011]

[0012] Where [n] represents the value at the nth sampling time, u xy_r e represents the actual value of the xy phase line voltage. x e y Represents the AC voltage of phases x and y, i x i y R represents the alternating current of phases x and y. x R y L represents the equivalent resistance of phases x and y. x L y T represents the filter inductance of phases x and y. s Indicates the switching period; x, y = a, b or c, and x ≠ y, xy = ab, bc or ca.

[0013] Furthermore, the method for calculating the expected value of the three-phase line voltage is as follows:

[0014]

[0015] Among them, u xy_c S represents the expected value of the xy phase line voltage. x S y U represents the average duty cycle of the switching transistors on the x and y phase bridge arms. dc This indicates DC voltage.

[0016] Furthermore, the method for determining the polarity of the deviation value of the three-phase line voltage is as follows:

[0017]

[0018] Where, Δu xy u represents the deviation value of the xy phase line voltage. th1 u th2 The first and second preset thresholds are represented by P+, P, Z, N, and N-, which represent five different polarities.

[0019] Further, determining the fault switch transistor by combining the polarity and phase of the deviation values ​​of the three-phase line voltages includes:

[0020] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are P, Z, and N respectively, and the voltage phases are... If it does not belong to (150°, 210°), then S1 is faulty;

[0021] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are N, Z, and P respectively, and the voltage phases... If it does not belong to (0,30°)∪(330°,360°), then S2 is faulty;

[0022] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are N, P, and Z respectively, and the voltage phases... If it does not belong to (270°, 330°), then S3 is faulty;

[0023] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are P, N, and Z respectively, and the voltage phases... If it does not belong to (90°, 150°), then S4 is faulty;

[0024] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are Z, N, and P respectively, and the voltage phases... If it does not belong to (30°, 90°), then S5 is faulty;

[0025] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are Z, P, and N respectively, and the voltage phases are... If it does not belong to (210°, 270°), then S6 is faulty;

[0026] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are P+, ​​N, and N respectively, then S1 and S4 are faults.

[0027] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are P, P, and N- respectively, then S1 and S6 are faults.

[0028] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are N-, P, and P respectively, then S2 and S3 are faults.

[0029] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are N, N, and P+ respectively, then S2 and S5 are faults.

[0030] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are N, P+, and N respectively, then S3 and S6 are faults.

[0031] When the polarities of the deviation values ​​of the line voltages of phases ab, bc, and ca are P, N-, and P respectively, then faults S4 and S5 occur.

[0032] Other dual-switch tube faults are diagnosed and located using two single-switch fault diagnoses.

[0033] The three-phase rectifier includes switching transistors S1-S6, with phase a switching transistors S1 and S2, phase b switching transistors S3 and S4, and phase c switching transistors S5 and S6. S1, S3, and S5 are upper bridge arm switching transistors, and S2, S4, and S6 are lower bridge arm switching transistors.

[0034] Secondly, the present invention provides a three-phase rectifier multiple switching transistor open-circuit fault diagnosis device based on voltage deviation, comprising:

[0035] The diagnostic signal acquisition module is used to acquire the rectifier's three-phase voltage, three-phase current, DC voltage, duty cycle of the switching transistors on the three-phase bridge arm, voltage phase calculated by the phase-locked loop, three-phase inductance value, three-phase equivalent resistance value, and switching cycle.

[0036] The voltage deviation calculation module is used to calculate the actual value of the three-phase line voltage based on Kirchhoff's voltage law, according to the three-phase voltage, three-phase current, three-phase inductance value, three-phase equivalent resistance value, and switching cycle; calculate the expected value of the three-phase line voltage based on the DC voltage and the average duty cycle of the switching transistors on the three-phase bridge arm; and obtain the deviation value of the three-phase line voltage by subtracting the expected value from the actual value.

[0037] A deviation polarity determination module is used to compare the deviation value of the three-phase line voltage with a first preset threshold and a second preset threshold to determine the polarity of the deviation value of the three-phase line voltage; wherein, the first preset threshold is less than the second preset threshold.

[0038] The fault diagnosis module is used to determine the faulty switch by combining the polarity of the deviation value of the three-phase line voltage with the voltage phase.

[0039] Thirdly, the present invention provides a machine-readable storage medium storing machine-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the three-phase rectifier multiple switching transistor open-circuit fault diagnosis method based on voltage deviation as described in the first aspect.

[0040] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0041] (1) The fault diagnosis process of the present invention only needs to use the existing sampling current value and intermediate calculation value in the rectifier control system, which has the advantages of simple implementation and small amount of calculation.

[0042] (2) By setting two thresholds and combining voltage phase information, various fault conditions of multiple switching transistors, including single-switch faults, sequential faults of two switching transistors, and simultaneous faults of two switching transistors, can be quickly diagnosed.

[0043] (3) By calculating the voltage deviation and combining it with the phase value, the fault can be located, which can realize the rapid diagnosis and location of the open circuit fault of the switching tube.

[0044] (4) It can accurately diagnose open circuit faults of three-phase rectifier switching transistors without adding extra hardware. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the main circuit topology and control system of a three-phase two-level rectifier provided in an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the calculation process of the three-phase rectifier multiple switch open circuit fault diagnosis method based on voltage deviation provided in the embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the control system of the three-phase two-level rectifier provided in an embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0049] like Figure 1As shown, the core components for power conversion in a typical three-phase two-level voltage-source rectifier are six switching transistors S1-S6 and six diodes D1-D6 connected in anti-parallel. The switching transistors for phase A are S1 and S2, for phase B they are S3 and S4, and for phase C they are S5 and S6. S1, S3, and S5 are referred to as the upper bridge arm switching transistors, and S2, S4, and S6 are referred to as the lower bridge arm switching transistors. The switching transistors and the filter inductor L are also shown. x Equivalent resistance R x Together with the filter capacitor C, they form the main circuit of the rectifier. The input terminal of the rectifier is connected to the three-phase AC voltage e. x The output terminal is connected to a load, which is equivalent to a resistor R. L The rectifier control system obtains the three-phase AC voltage e of the main circuit through current and voltage sensors. x Alternating current i x DC voltage value U dc The system calculates and outputs drive signals s1-s6 to control the operation of each power transistor. Here, x = a, b, or c, representing the phase in which the transistor is located.

[0050] Based on this, such as Figure 2 As shown, this invention proposes a method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation, comprising the following steps:

[0051] (1) Obtain the three-phase voltage, three-phase current, DC voltage, duty cycle of the switching transistors on the three-phase bridge arm, voltage phase calculated by the phase-locked loop, three-phase inductance value, three-phase equivalent resistance value and switching cycle of the rectifier.

[0052] In this embodiment, relevant signals for diagnostics are obtained from the rectifier control system, wherein the relevant signals include the rectifier AC side three-phase voltage sampling signal e. x [n]、e x [n-1], Three-phase current sampling signal i x [n]、i x [n-1], DC voltage sampling signal U dc [n]、U dc [n-1], and the duty cycle S of the switching transistors on the three-phase bridge arm calculated by the space vector modulation method in the control system. x [n] and the voltage phase calculated by the phase-locked loop. There is also the constant value of the three-phase filter inductor L set in the control system. x Equivalent resistance R x The first preset threshold u th1 Second preset threshold u th2 , with the switching period T s [n] represents the value at the nth sampling time.

[0053] (2) Based on the three-phase voltage, three-phase current, three-phase inductance, three-phase equivalent resistance and switching cycle, calculate the actual value of the three-phase line voltage according to Kirchhoff's voltage law; calculate the expected value of the three-phase line voltage according to the DC voltage and the average duty cycle of the switching transistors on the three-phase bridge arm; and obtain the deviation value of the three-phase line voltage by subtracting the expected value from the actual value.

[0054] In this embodiment, the actual value of the three-phase line voltage is calculated as follows:

[0055]

[0056] Where [n] represents the value at the nth sampling time, u xy_r e represents the actual value of the xy phase line voltage. x e y Represents the AC voltage of phases x and y, i x i y R represents the alternating current of phases x and y. x R y L represents the equivalent resistance of phases x and y. x L y T represents the filter inductance of phases x and y. s Indicates the switching period; x, y = a, b or c, and x ≠ y, xy = ab, bc or ca.

[0057] The method for calculating the expected value of the three-phase line voltage is as follows:

[0058]

[0059] Among them, u xy_c S represents the expected value of the xy phase line voltage. x S y U represents the average duty cycle of the switching transistors on the x and y phase bridge arms. dc This indicates DC voltage.

[0060] The method for calculating the deviation of the three-phase line voltage is as follows:

[0061] Δu xy [n] = u xy_c [n]-u xy_r [n]

[0062] Where, Δu xy This represents the deviation value of the xy phase line voltage.

[0063] (3) Compare the deviation value of the three-phase line voltage with the first preset threshold and the second preset threshold to determine the polarity of the deviation value of the three-phase line voltage; wherein the first preset threshold is less than the second preset threshold.

[0064] In this embodiment, under ideal conditions during normal operation, the deviation of the three-phase line voltage is 0. However, due to errors caused by factors such as sampling, dead zone, parameter measurement, and noise, the actual deviation of the three-phase line voltage fluctuates around 0 during normal operation. To avoid misdiagnosis, a threshold u is set. th1 u th2 The deviation of the three-phase line voltage is compared with two threshold values ​​to obtain the polarity of the deviation value. The polarity is defined as follows:

[0065]

[0066] Preferably, u th2 Much larger than u th1 .

[0067] (4) Determine the fault switch tube by combining the polarity of the deviation value of the three-phase line voltage with the voltage phase.

[0068] In this embodiment, voltage phase is considered. The diagnostic rules are shown in Table 1.

[0069] Table 1 Diagnostic Rules

[0070]

[0071] The diagnostic rules shown in Table 1 are explained in detail below.

[0072] Three-phase PWM rectifier such as Figure 1 As shown, in the main circuit, e abc It is the three-phase grid line voltage (e ab e bc e ca This can be obtained through sampling; u ab u bc u ca It is the AC line voltage of the three-phase rectifier, i a i b i c It is the AC side current, which can be obtained through sampling, with the direction shown by the arrow in the figure as the positive direction.

[0073] In engineering applications, three-phase PWM rectifiers mostly employ dual closed-loop control and space vector modulation. For example... Figure 3 As shown, the dual closed-loop control is based on PI control in a synchronously rotating dq coordinate system, where the outer voltage loop is used to control the output voltage (U) of the three-phase rectifier. dcThis stabilizes the rectifier at the target voltage, with the inner current loop outputting the desired voltage across the three-phase bridge arms. Three-phase rectifiers typically operate in unity power factor mode, meaning that for the power grid, the phase voltage and phase current remain in phase. The controller's control objective requires a q-axis current i q The reference value is 0, at which point the d-axis current i d The reference value is the output value of the outer voltage loop.

[0074] Define the switch state function:

[0075]

[0076] Define the average switching state function during the switching cycle, which is the average duty cycle of the switching transistors in the upper arm of phase x:

[0077]

[0078] Use S x_c The desired average switching function of the control system is represented by S. x_r Let the actual equivalent average switching function be represented, then:

[0079] u xy_r [n] = (S x_r [n]-S y_r [n])*U dc

[0080] u xy_c [n] = (S x_c [n]-S y_c [n])*U dc

[0081] When the rectifier is working normally:

[0082] u xy_r [n] = u xy_c [n] = (S x_r [n]-S y_r [n])*U dc

[0083] When a fault occurs, S x_c ≠S x_r Therefore, u xy_r [n]≠u xy_c [n].

[0084] Since the rectifier operates at unity power factor, the phase of the in-phase voltage is the same as the phase of the current. One fundamental cycle can be divided into six regions based on the sign of the current, as shown in Table 2.

[0085] Table 2. Division of Fundamental Wave Period

[0086]

[0087] ① Single tube failure scenario (taking S1 failure as an example)

[0088] when i a >0, the current path is D1 or S2; when i a =0, no current flows; when i = 0, no current flows; a <0, the current path is S1 or D2. The analysis of phases b and c is similar, yielding the last column of Table 2. Therefore, a fault in S1 only occurs when i a It will be affected when it is less than 0.

[0089] when i a When S < 0 and S1 fails, S a_c >S a_r ,so

[0090] Δu ab [n]>0

[0091] Δu bc [n] = 0

[0092] Δu ca [n]<0

[0093] Based on the above conditions, fault diagnosis under single-tube failure can be achieved.

[0094] ② Fault situation of two in-phase transistors (taking S1 and S2 faults as an example)

[0095] Based on the previous analysis, the S1 fault only occurs when i a When <0, it will be affected; S2 fault only occurs when i... a When the value is >0, it will be affected. There is no moment when it is affected by two switch faults at the same time. Therefore, as long as we diagnose the two single tube faults at different times according to the analysis in ①, we can achieve the diagnosis of dual tube faults in this situation.

[0096] ③ Fault scenarios involving two tubes on different phases and sides (taking S1 and S4 faults as examples)

[0097] According to Table 1, a fundamental frequency cycle under this fault condition can be divided into four regions, as shown in Table 3.

[0098] Table 3. Division of Fundamental Wave Period

[0099]

[0100] When only a single transistor affects the normal operation of the rectifier, the fault phenomenon is the same as that of the single transistor fault in ①. When both transistors affect the normal operation of the rectifier, the residuals of the three line voltages deviate. Based on the situation where the deviation of one line voltage is much higher than that of a single-phase fault, a higher threshold can be set to directly locate the dual-transistor fault. Alternatively, one single transistor can be diagnosed first and then another single transistor can be diagnosed to achieve dual-transistor fault diagnosis, depending on the phase at which the fault occurs.

[0101] ④ Fault scenarios involving two tubes on different sides of the same tube (taking S1 and S3 faults as examples)

[0102] According to Table 1, a fundamental frequency cycle under this fault condition can be divided into four regions, as shown in Table 4.

[0103] Table 4. Division of Fundamental Wave Period

[0104]

[0105] Since at (210°, 270°), i a i b Both are less than 0, at this time the C-phase current i c >0. Because S1 and S3 are faulty, the current can only freewheel through D2 and D4. Therefore, Δu ab The state can be unpredictable, potentially greater than, less than, or equal to 0. When it equals 0, it can lead to a misdiagnosis as a single-tube fault S6. To avoid this situation, this area should be avoided when diagnosing single-tube faults. The diagnosis of this dual-tube fault is achieved by diagnosing two consecutive single-tube faults.

[0106] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation, characterized in that, Includes the following steps: Obtain the three-phase voltage, three-phase current, DC voltage, duty cycle of the switching transistors on the three-phase bridge arm, voltage phase calculated by the phase-locked loop, three-phase inductance value, three-phase equivalent resistance value, and switching cycle of the rectifier; Based on the three-phase voltage, three-phase current, three-phase inductance, three-phase equivalent resistance, and switching cycle, the actual value of the three-phase line voltage is calculated according to Kirchhoff's voltage law; the expected value of the three-phase line voltage is calculated based on the DC voltage and the average duty cycle of the switching transistors on the three-phase bridge arm; the deviation value of the three-phase line voltage is obtained by subtracting the expected value from the actual value. The polarity of the three-phase line voltage deviation is determined by comparing it with a first preset threshold and a second preset threshold; wherein the first preset threshold is less than the second preset threshold; the method for determining the polarity of the three-phase line voltage deviation is as follows: in, express xy The deviation value of the phase line voltage, , This represents the first preset threshold and the second preset threshold. P+、 P, Z, N, N- Represents 5 different polarities; Based on the polarity and phase of the deviation values ​​of the three-phase line voltages, the fault switch transistor is determined, including: when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively P, Z, N And voltage phase φ PLL If it does not belong to (150°, 210°), then S1 is faulty; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively N, Z, P And voltage phase φ PLL If it does not belong to (0,30°)∪(330°,360°), then S2 is faulty; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively N, P, Z And voltage phase φ PLL If it does not belong to (270°, 330°), then S3 is faulty; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively P, N, Z And voltage phase φ PLL If it does not belong to (90°, 150°), then S4 is faulty; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively Z, N, P And voltage phase φ PLL If it does not belong to (30°, 90°), then S5 is faulty; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively Z, P, N And voltage phase φ PLL If it does not belong to (210°, 270°), then S6 is faulty; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively P+, N, N If S1 and S4 fail; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively P, P, N- If S1 and S6 fail; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively N-, P, P If S2 and S3 fail; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively N, N, P+ If S2 and S5 fail; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively N, P+, N If S3 and S6 fail; when ab Mutually, bc Mutually, ca The polarities of the phase line voltage deviation values ​​are respectively P, N-, P If S4 and S5 fail; Other dual-switch tube faults are diagnosed and located using two single-switch fault diagnoses. The three-phase rectifier includes switching transistors S1-S6. a The phase switch transistors are S1 and S2. b The phase switch transistors are S3 and S4. c The phase switch transistors are S5 and S6, and S1, S3 and S5 are upper bridge arm switches, while S2, S4 and S6 are lower bridge arm switches.

2. The method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation as described in claim 1, characterized in that, The method for calculating the actual value of the three-phase line voltage is as follows: Where [n] represents the value at the nth sampling time, express xy The actual value of the phase line voltage, , express x , y AC voltage of phase, , express x , y Alternating current of phase, , express x , y The equivalent resistance of the phase, , express x , y Phase filter inductor, Indicates the switching cycle; x , y = a , b or c ,and x ≠ y , xy = ab、bc or ca .

3. The method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation according to claim 2, characterized in that, The method for calculating the expected value of the three-phase line voltage is as follows: in, express xy The expected value of the phase line voltage. , express x , y The average duty cycle of the switching transistors on the phase bridge arm. This indicates DC voltage.

4. A three-phase rectifier multiple switching transistor open-circuit fault diagnosis device based on voltage deviation, characterized in that, The method for diagnosing open-circuit faults of multiple switching transistors in a three-phase rectifier based on voltage deviation, as described in any one of claims 1-3, includes: The diagnostic signal acquisition module is used to acquire the rectifier's three-phase voltage, three-phase current, DC voltage, duty cycle of the switching transistors on the three-phase bridge arm, voltage phase calculated by the phase-locked loop, three-phase inductance value, three-phase equivalent resistance value, and switching cycle. The voltage deviation calculation module is used to calculate the actual value of the three-phase line voltage based on Kirchhoff's voltage law, according to the three-phase voltage, three-phase current, three-phase inductance value, three-phase equivalent resistance value, and switching cycle; calculate the expected value of the three-phase line voltage based on the DC voltage and the average duty cycle of the switching transistors on the three-phase bridge arm; and obtain the deviation value of the three-phase line voltage by subtracting the expected value from the actual value. A deviation polarity determination module is used to compare the deviation value of the three-phase line voltage with a first preset threshold and a second preset threshold to determine the polarity of the deviation value of the three-phase line voltage; wherein, the first preset threshold is less than the second preset threshold. The fault diagnosis module is used to determine the faulty switch by combining the polarity of the deviation value of the three-phase line voltage with the voltage phase.

5. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores machine-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the three-phase rectifier open-circuit fault diagnosis method based on voltage deviation as described in any one of claims 1 to 3.

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